Electrical heaters are commonly used in air data probes for aircraft to protect against icing conditions. The heater in an air data probe is typically designed to provide for de-icing of the air data probe before flight of an aircraft, and de-icing or anti-icing of the air data probe during flight.
Current governmental icing regulations now require air data probes to be exposed to significantly more demanding icing conditions than in the past. More heat can be used to protect against these conditions. However, the amount of power that can be applied to an air data probe is limited by how hot it will get while energized with the aircraft on the ground on a hot day. In addition, reliability issues have typically limited active power management techniques to reduce air data probe temperatures when the aircraft is on the ground.
Typically, each air data probe in an aircraft is connected individually to the aircraft power system, which can result in very hot conditions when operating the air data probe while the aircraft is parked or taxiing to a runway. This is true, even when using a positive temperature coefficient of resistance material for the probe heater. The increased icing threat defined in the icing regulations compounds this problem.